Drafting instrument



Feb. 20, 1951 L.. VEYRET ET AL DRAFTING INSTRUMENT Filed Feb. 26, 1948 INVENTORS oa/s Vey/"ef eo/ges 6'@ ffra y Ey W2K/Hy Patented Feb. 20, 1951 DRAFTING INSTRUMENT Louis Veyret, N euilly-sur-Seine, and Georges Geffroy, Paris, France, assignors to La Cellophane, Paris, France, a French company Application February 26, 1948, Serial No. 11,246

1n France June 6, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires June 6, 1965 3 Claims.

This invention relates to drafting instruments of the type having a head carrying two mutually perpendicular rules and supported by a system of deformable parallelograms, permitting the combination of rules to be displaced parallel to themselves over the entire extent oi the drawing board, While the rules themselves may be angularly adjusted and set in Various selected positions with reference to their support.

The invention relates particularly to a drafting instrument head, i. e. a linkage mechanism between the rules and their deformable support. The invention provides a knob rotatably mounted about a vertical axis on a cylindrical bearing xed to the system of rules, and acting, iirst, on a brake mechanism permitting xed adjustment of the system of rules in various desired positions upon its support; and, second, upon a lock working in conjunction with corresponding holes in the support to permit the system of rules to be locked in a series of predetermined angular positions.

Other features of the invention will be apparent from the followingr description taken in connection with the accompanying drawings in which certain specic embodiments are set forth for purposes of illustration.

In the drawings:

Fig. 1 is a vertical section showing one form of drafting instrument head embodying the invention;

Fig. 2 is a vertical section showing another embodiment of the invention;

Fig. 3 is a partial bottom plan View of the device shown in Fig. 2;

Figs. 4 to 6 are vertical sections showing other embodiments of the invention;

Fig. 'I is a partial top plan view of the device of Fig. 6; and

Fig. 8 is a diagrammatic view showing the device applied to a drawing board.

In reference to the drawings, and in the figures as a whole, I designates the support for the movable head, which is shiftable over the drawing board by means of parallelogram links as shown in Fig. 8. A set of rules are carried by a head 2 pivoted to the support I. An operating knob 3 is rotatably mounted on a bearing d iixed to the head 2. A brake rod 5 carries a shoe 6 and is supported by a nut 'I engaging threads cut on knob 3. A plunger 9 ends in a conical tip and carries a projection I l! resting on a helical groove II on the knob 3. I2 is a retaining spring for the plunger 9 which engages conical holes I3 in the support I located on the periphery of a circular arc.

In Fig. 1 the head 2 is located above the support I, and the plunger 9 slides in a coaxial bore in the bearing 4, in which it is keyed to slide without rotation. The groove il, ending in a horizontal portion M, is accommodated in the internal wall of the knob 3, the bearing 4 being recessed to receive the projection le. The knob 3 is held in Vertical position on the bearing 4 by spurs I5 engaging a horizontal slot in the bearing 4l. The threads 8 are cut on the outer Wall of the knob 3, and the nut "I, coaxial with bearing Il, knob 3 and plunger 9, surrounds the knob 3.. The rod 5, attached to the nut 'I by threads it is displaced laterally with respect to the knob 3. When the nut l rises, the shoe 6 bears with its upper face upon the lower face of the edge of the support I. The screw pitch of threads 8 is such that when the knob 3 is turned clockwise, the nut 'I is lowered, taking with it the rod 5, the groove I I being such that the plunger 9 likewise descends in the same motion.

In the position of Fig. 1, the brake is off and the plunger 9, engaging a hole I3 and retained by its spring I2, locks the movable portion 2 to the support I in a position determined by the location of the hole I3. If it is desired to displace and set the movable portion 2 into some position between two of the holes I3, the knob 3 is turned counterclockwise. The projection Hl then rises on the groove I I, and the plunger 3 is raised until the projection I0 reaches the horizontal portion I4 of the groove. In this motion, the plunger 9 is withdrawn from the hole I3, thus `releasing the movable portion 2, and the rod 5 is raised slightly, though without making contact between the shoe 6 and the support I. The movable portion 2 is thus free and maybe turned to the desired position. To keep it in that position, the knob 3 is further turned counterclockwise, the projection I0 thus passing over the horizontal portion I4 of the groove. The plunger 9 remains in disengaged position, the rod 5 continues to rise, and the shoe 6 is brought to bear against the support I, thus securely clamping the movable portion 2 to the support I.

In Figs. 2 and 3, the mechanism is the same as in Fig. 1, but the rod e is coaxially placed in the interior of the plunger 9, and the nut 'l is permanently tightened and locked in the interior of the knob 3. When the knob 3 is turned, the rod 5 is screwed or unscrewed, as the case may be, in the nut "E, which as aforesaid turns with the knob 3. The holes i3 are formed partially in the support I and partially in a part Il fixed to the movable portion 2 (see Fig. 3). The vertical 3 guidepin I8 of the lock B is displaced in a vertical groove I9 in the bearing 4, in such a manner as to prevent any rotation of the plunger 9.

Operation is the same as in Fig. 1.

In Fig. 4', the movable' portion12 is placedbelow the support I and the operating mechanism is mounted on a bracket 2l] iixed to the movable portion 2 and surmounting the support I. The

rod 5 is coaxially placed in the interior.- ofv the.-

bearing 4 supporting the knob 3, and the plunger 9 slides on the exterior of the knob 31m a cylin drical part 2i fixed to the bracket 28. The proj-- jection IU, which moves in a notch in the'part 2'I`, acts upon a lever 22 pivoting' on a shaft 2,3 ina bearing 24 Xed to the bracket 2D, thezfre'eend.

and the plunger e, carriesa follower 25 acting directly on the cam surface II.-

It will be noted that in the case of Figs. lto- 5, the plunger 9l may readily be removed and omitted, in which case the mechanism may be set by the brake alone.`

The mechanism of Figs.Y 6 and- 7. is analogous to:

that of Figs.v 2 and` 3, but the rod 5'is elevated` simply by the risingl ofV the plunger 9the rod- 5- not being connected to the kncb 3 and having a.

head 2tt which-.may be brought to rest on a-shoulder 2l in the upper partof'the plunger` 9; A weak spring 28' retains-the rod 5.7upward. lI'he horizon tall portion I4 of the-incline is eX-tendedto form` a second helical groove-29. The holes I3 arefen-V tirely accommodated in the support I., being. joined by a slot 30 to passthefrodi (Fig.- '7),the two portions of the slot 39 being connectedbelowby an annular channel 3I- witha U-shaped cross-v sectie-n` to accommodate Vtheslnoe E.

In turning the knob V3 counterclockwise, anim-- tial upwards motion of theplunger 9, is produced, thus withdrawing it from the hole Island` comfpressin-g the' spring 28. In the horizontal portion H301 the incline, the movable portion 2 is free-y whereupon thef additional rise of'` the projection.f I, whenV the latter follows the groove 29, lifts the' rod 5 by its head 2.6 on the1shoulder'2-'I and clamps the shoe against the support' I.

Naturally, theY invention is not restricted to the specic forms illustrated and described, which have been selected by way of example; The invention is only to be limited in accordance with the scope of the following claims.

What is claimed is:

1. In a drafting instrument of the type comprising a support mounted to move over a board and a head carrying a rule pivoted to said support, adjusting and locking mechanism for said head comprising a base plate having an arcuate roW'cfholes Xed to said support, a sleeve xed to said head, a plunger slidable vertically in said sleeve and adaptedto enter a selected hole, a bearing member mounted on said head, a knob journalled on said bearing member to rotate about a vertical axis, said knob having a helical cam surface, a cam follower connected to ride on saidsuracefor elevating said plunger, said surfacel terminating in a horizontal portion so arranged that initial turning of the knob lifts the plunger and further turning of the knob retains the plunger elevated, a brake mechanism comprising a rod sli'dably mounted'on said head and carrying a brake Shoe to clamp against the under surface of saidibase plate, a nut carrying said rod and said nut being concentric with and.

threaded VtoA said knob and being fixedl against rotationso as to be raisedor lowered by turning of theiknob, the threads on said. nut. having a pitch such that rotation of the knob inY a directionito raise said plunger and to a` position corresponding to the horizontal vportion of saidcamsurface.

also applies said brake.

2. A drafting instrument, as set forth in claim 1in which the plunger. is mounted'coaxially with 3. A drafting'instrument, asset forth in claim 1, in which. said cam surface comprises agroove` on the inner surfacev of said, knob and said cam.

follower comprises apin attached to said plunger and' engaging said'groove.'`

LOUISVEYRET. GEORGES GEFFROY.

REFERENCES CITED Thefol-lowing" references' are of record in the file of this patent:

UNITED. STATES PATENTS 

